The bleeding child. Part I: primary hemostatic disorders

Delta Storage Pool Deficiency: A Pediatric Case Report and Review of the Literature

Platelet storage deficiencies are a heterogeneous group of bleeding disorders of variable severity caused by decreased number or content of platelet granules. We present the case of a 10-year-old patient with no personal history of previous bleeding who was admitted to the emergency department due to menorrhagia and mucocutaneous pallor. Common disorders of primary and secondary hemostasis were ruled out. Subsequently, a study of electron microscopy of platelets was performed, which reported the presence of alpha granules with a decreased number of dense granules. Currently, the patient receives treatment with tranexamic acid during menstrual periods, supplementation with ferrous sulfate, and oral contraceptives, achieving control of bleeding episodes.

Valsalva purpura on the face of a 7-year-old child

Valsalva purpura refers to purpura resulting from performing the Valsalva maneuver, a forced expiratory effort against a closed glottis. There are limited reported cases of Valsalva purpura in children, specifically on the cheeks. We present the case of a 7-year-old child who developed Valsalva purpura on his cheeks after performing the Valsalva maneuver during deep breathing exercises by holding his breath underwater during his swimming sessions. This article overviews the relationship between the Valsalva maneuver, purpura, and similar cases.

Primary Hemostasis Disorders as a Cause of Heavy Menstrual Bleeding in Women of Reproductive Age

Heavy menstrual bleeding (HMB) is a common clinical condition affecting adolescent and adult women and compromising their quality of life. Primary hemostasis disorders, affecting platelet plug formation, can be the underlying cause of HMB. They comprise a heterogeneous group of diseases with Von Willebrand disease (VWD) being the most commonly diagnosed; other disorders in this group that have been linked to HMB include (a) Glanzmann thrombasthenia, (b) Bernard-Soulier syndrome, (c) Hermansky-Pudlak syndrome, (d) immune thrombocytopenia (ITP), and (e) Ehlers-Danlos syndromes (EDS) and hypermobility spectrum disorders (HSD). Diagnosing these diseases can be challenging, as the basic laboratory investigations can be within the normal range. Thus, identification of specific clinical features and a thorough hematologic workup can be very important, providing the correct diagnosis. Proper diagnosis of the underlying disorder is important, as management may vary accordingly. Although disease-specific management guidelines exist for some of these disorders such as VWD and ITP, due to the rarity of most primary hemostasis disorders, the best approach for the management of HMB in these women remains elusive. The goal of this study was to create an informative, comprehensive review of the primary hemostasis disorders that have been linked to HMB. This study provides a summary of the basic published information regarding epidemiology, pathophysiology, clinical phenotype, diagnosis, and treatment of HMB in those diseases and serves as a reference guide for further reading.

Focus on MicroRNAs as Biomarker in Pediatric Diseases

BACKGROUND

MiRNAs are a class of small non-coding RNAs that are involved in the post-transcriptional regulation of gene expression. MiRNAs are considered a class of epigenetic biomarkers. These biomarkers can investigate disease at different stages: diagnosis, therapy or clinical follow-up.

OBJECTIVE

The aim of this paper is to highlight the innovative use of miRNAs in several childhood diseases.

METHODS

We conducted a literature review to search the usage of miRNAs in pediatric clinical routine or experimental trials.

RESULTS

We found a possible key role of miRNAs in different pediatric illnesses (metabolic alterations, coagulation defects, cancer).

CONCLUSION

The modest literature production denotes that further investigation is needed to assess and validate the promising role of miRNAs as non-invasive biomarkers in pediatric disorders.

Standardization of Prothrombin Time/International Normalized Ratio (PT/INR)

The prothrombin time (PT) represents the most commonly used coagulation test in clinical laboratories. The PT is mathematically converted to the international normalized ratio (INR) for use in monitoring anticoagulant therapy with vitamin K antagonists such as warfarin in order to provide test results that are adjusted for thromboplastin and instrument used. The INR is created using two major PT 'correction factors', namely the mean normal PT (MNPT) and the international sensitivity index (ISI). Manufacturers of reagents and coagulometers have made some efforts to harmonizing INRs, for example, by tailoring reagents to specific coagulometers and provide associated ISI values. Thus, two types of ISIs may be generated, with one being a 'general' or 'generic' ISI and others being reagent/coagulometer-specific ISI values. Although these play a crucial role in improving INR results between laboratories, these laboratories reported INR values are known to still differ, even when laboratories use the same thromboplastin reagent and coagulometer. Moreover, ISI values for a specific thromboplastin can vary among different models of coagulometers from a manufacturer using the same method for clot identification. All these factors can be sources of error for INR reporting, which in turn can significantly affect patient management. In this narrative review, we provide some guidance to appropriate ISI verification/validation, which may help decrease the variability in cross laboratory reporting of INRs.

The Implementation of a Pediatric Nonaccidental Trauma Evaluation Protocol: A Quality Improvement Analysis

BACKGROUND

Pediatric nonaccidental trauma (NAT) accounts for more than 1500 deaths annually and is a source of incalculable lifelong morbidity. Evidence-based NAT evaluation protocols are available; however, compliance studies are lacking. Here, we analyze the quality of implementation of a new NAT evaluation protocol.

METHODS

A review of registry data from a level 3 trauma center was performed for patients with a suspicion of NAT from September 2014 to May 2016. Compliance rates and results of 2 new age-based evaluation protocols were examined before (phase 1) and after (phase 2) a multidisciplinary conference was initiated to improve performance.

RESULTS

Seventy-five children underwent evaluation for NAT during the study period. In phase 1, median compliance rates with all of the protocol elements were low (63%). After a bimonthly multidisciplinary conference was initiated, compliance rates improved to 75%. Some elements, which were often missed, were found to be clinically irrelevant. If only clinically relevant elements were included, median compliance in phase 2 is 86%.

CONCLUSIONS

Compliance with a new protocol for NAT was improved with the institution of a multidisciplinary conference. Protocol elements, which are shown to be clinically unnecessary, have also been identified and will be eliminated.

[Coagulation function and hemorrhagic diseases in preterm infants with different gestational ages]

OBJECTIVE

To study the correlation between coagulation function and gestational age in preterm infants and the possible value of coagulation function measurement in predicting hemorrhagic diseases.

METHODS

The clinical data of preterm infants who were hospitalized between September 2016 and August 2017 were collected. The coagulation indicators were measured within 2 hours after birth. According to the gestational age, the preterm infants were divided into late preterm infant group (n=322), early preterm infant group (n=241) and extremely/very early preterm infant group (n=128). Coagulation function was compared among the three groups, as well as between the preterm infants with and without hemorrhagic diseases within 3 days after birth.

RESULTS

There were significant differences in thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen degradation product (FDP) and D-dimer (DD) among the three groups (P<0.05). APTT, PT, FDP and DD were negatively correlated with gestational age, while TT was positively correlated with gestational age (P<0.05). The preterm infants with hemorrhagic diseases had a longer APTT and a higher level of DD (P<0.05).

CONCLUSIONS

Coagulation function gradually becomes mature in preterm infants with the increase in gestational age. Abnormal APTT and DD indicate that preterm infants may have a higher risk of hemorrhagic diseases.

Validation of flow cytometric analysis of platelet function in patients with a suspected platelet function defect

Essentials The diagnosis of mild platelet function disorders (PFDs) is challenging. Validation of flow cytometric testing in patients with suspected PFDs is required. Flow cytometry has added value to light transmission aggregometry (LTA) in diagnosis of PFDs. There is fair agreement in diagnosing PFDs between LTA and flow cytometry.

SUMMARY

Background Light transmission aggregometry (LTA) is the most commonly used test for the diagnosis of platelet function disorders (PFDs), but has moderate sensitivity for mild PFDs. Flow cytometry has been recommended for additional diagnostics of PFDs but is not yet standardized as a diagnostic test. We developed a standardized protocol for flow cytometric analysis of platelet function that measures fibrinogen binding and P-selectin expression as platelet activation markers in response to agonist stimulation. Objectives To determine the additional value of flow cytometric platelet function testing to standard LTA screening in a cross-sectional cohort of patients with a suspected PFD. Methods Platelet function was assessed with flow cytometry and LTA in 107 patients suspected of a PFD in whom von Willebrand disease and coagulation factor deficiencies were excluded. Both tests were compared in terms of agreement and discriminative ability for diagnosing patients with PFDs. Results Out of 107 patients, 51 patients had an elevated bleeding score; 62.7% of the patients had abnormal platelet function measured with flow cytometry and 54.2% of the patients were abnormal based on LTA. There was fair agreement between LTA and flow cytometry (κ = 0.32). The discriminative ability of flow cytometric analysis in patients with an elevated bleeding score was good (AUC 0.82, 0.74-0.90), but moderate for LTA (AUC 0.70, 0.60-0.80). Both tests combined had a better discriminative ability (AUC 0.87, 0.80-0.94). Conclusion Flow cytometric analysis of platelet function has added value in diagnostics of PFDs in patients with unexplained bleeding tendency.

The Role of Platelet and its Interaction with Aspirin

<p>Introduction. Platelets are not strictly “cells”, they are cytoplasmic fragments that are produced by the division of the cytoplasm of the megakaryocytes in the bone marrow; among its properties of adhesion and aggregation, platelets are involved in primary hemostasis, thrombosis, repair and tissue regeneration processes. To modify the pro-thrombotic platelet properties aspirin (ASA) is provided, which allows blocking the synthesis of prostaglandins in order to irreversibly inhibit the COX1 and prevent platelet aggregation. The current guidelines govern the use of aspirin in the prevention of cardiovascular diseases. Objective. In this review paper graphics were created to facilitate the understanding of platelets and its interaction with various physiological and pathological processes. Methodology. A literature review of a total of 74 documents such as articles and books was carried out; it was obtained from bibliographic searches in the following databases: Scielo, NEJM, Elsevier, Pubmed, Redalyc, Wiley, Springer, ScienceDirect, BVS, Nature Riviews, EBSCO, Naxos (databases offered by the University of Cauca). Mendeley free access program was used for the management and organization of information. Conclusion. It is recognized the role of platelet in different physiopathological processes and thus its interaction with aspirin, preventing its aggregation and thrombus formation in the spleen and other organs, this way contributing to the prevention of future cardiovascular events.</p>

Contemporary developments in the discovery of selective factor Xa inhibitors: A review

Thrombosis is a leading cause of death in cardiovascular diseases such as myocardial infarction (MI), unstable angina and acute coronary syndrome (ACS) in the industrialized world. Venous thromboembolism is observed in about 1 million people every year in United States causing significant morbidity and mortality. Conventional antithrombotic therapy has been reported to have several disadvantages and limitations like inconvenience in oral administration, bleeding risks (heparin analogs), narrow therapeutic window and undesirable interactions with food and drugs (vitamin K antagonist-warfarin). The unmet medical demand for orally active safe anticoagulants has generated widespread interest among the medicinal chemists engaged in this field. To modulate blood coagulation, various enzymes involved in the coagulation process have received great attention as potential targets by various research groups for the development of oral anticoagulants. Among these enzymes, factor Xa (FXa) has remained the centre of attention in the last decade. Intensive research efforts have been made by various research groups for the development of small, safe and orally bioavailable FXa inhibitors. This review is an attempt to compile the research work of various researchers in the direction of development of FXa inhibitors reported since 2010 onward.

Patient safety in South Africa: PICU adverse event registration*

OBJECTIVE

Adverse event registration is a means to improve patient safety in a PICU. So far it has been used in European and North American countries mainly. We studied adverse events in a South African setting with the aims to 1) assess rates and types of adverse events with two different registration methods and 2) describe characteristics of patients experiencing adverse events.

DESIGN

This study consisted of 1) a retrospective audit of randomly selected patient records and 2) a prospective observational study of real-time registration of AEs during ward rounds. Adverse events were identified using the Child Health Corporation of America - Pediatric Pharmacy Advocacy Group PICU trigger tool.

SETTING

A multidisciplinary 20 bed PICU at the Red Cross War Memorial Children's Hospital in Cape Town.

PATIENTS

The retrospective section of the study involved 80 randomly selected patients who had been discharged from the PICU, and the prospective study involved patients who were present in the PICU between March and June 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The retrospective audit identified 260 adverse events in 61 patients (50.8 per 100 patient days). Nineteen patients (24%) did not have any adverse events. Catheter complications, hypoglycemia, and endotracheal tube malpositioning requiring repositioning were most frequent. Prospective registration during 58 ward rounds revealed 272 adverse events in 236 patients (27.2 per 100 patient days), particularly catheter complications, nosocomial infection, and surgical complications. Hundred thirty-two patients of the total 236 patients (56%) did not experience an adverse event. Patients experiencing adverse events underwent mechanical ventilation significantly more frequently. Length of stay was significantly associated with number of adverse events.

CONCLUSIONS

The trigger tool method identifies a higher adverse event rate compared with real-time registration. Each method has a unique contribution to yield types of adverse events.

Rare bleeding disorders in children: identification and primary care management

Bleeding symptoms are common in healthy children but occasionally may indicate an underlying congenital or acquired bleeding diathesis. The rare bleeding disorders (RBDs) comprise inherited deficiencies of coagulation factors I (congenital fibrinogen deficiencies), II, V, VII, X, XI, and XIII and combined factor deficiencies, most notably of factors V and VIII and of vitamin K-dependent factors. These disorders often manifest during childhood and may present with recurrent or even serious or life-threatening bleeding episodes, particularly during the neonatal period. Accordingly, primary care and other nonhematologist pediatric providers should be familiar with the clinical presentation and initial evaluation of these rare disorders. Bleeding manifestations generally vary within the same RBD and may be indistinguishable from 1 RBD to another or from other more common bleeding disorders. Serious bleeding events such as intracranial hemorrhage may be heralded by less serious bleeding symptoms. The results of initial coagulation studies, especially prothrombin time and activated partial thromboplastin time, are often helpful in narrowing down the potential factor deficiency, with factor XIII deficiency being an exception. Consultation with a hematologist is advised to facilitate accurate diagnosis and to ensure proper management and follow-up. The approach to bleeding episodes and invasive procedures is individualized and depends on the severity, frequency, and, in the case of procedures, likelihood of bleeding. Prophylaxis may be appropriate in children with recurrent serious bleeding and specifically after life-threatening bleeding episodes. When available, specific purified plasma-derived or recombinant factor concentrates, rather than fresh frozen plasma or cryoprecipitate, are the treatment of choice.

Genotyping and phenotyping of platelet function disorders

The majority of patients with platelet function disorders (PFDs) have normal platelet counts and mild day-to-day bleeding symptoms, but are at risk of major hemorrhage at times of trauma, surgery, or childbirth. This group is challenging to investigate, because the assays are often time-intensive and labour-intensive, and interpretation is difficult, especially in patients with mild disorders. In addition, interuser variability in performance of the assays, including the currently accepted gold standard, light transmission aggregometry, makes the results difficult to compare between laboratories. Furthermore, a similar pattern of mucocutaneous bleeding is seen in disorders in other components of the hemostatic pathway, including type 1 von Willebrand disease (VWD). We have undertaken an extensive investigation of patients with clinically diagnosed excessive bleeding, using a genotyping and platelet phenotyping approach based on lumi-aggregometry, and other specialist tests of platelet function, in combination with Sanger and next-generation sequencing (NGS). We found a functional defect in ~ 60% of patients, the majority being associated with feedback pathways of platelet activation. Function-disrupting mutations were identified in known and novel genes, and coinheritance with other genetic disorders of hemostasis, including type 1 VWD, was shown. A significant number of mutations are heterozygous and unlikely to cause extensive bleeding in isolation, consistent with incomplete penetrance of inheritance of bleeding disorders and a multifactorial etiology for excessive bleeding in many patients. Mucocutaneous bleeding is a complex trait, and this has important implications for NGS in the assessment of a PFD.

Determination of ATP and ADP Secretion from Human and Mouse Platelets by an HPLC Assay

BACKGROUND

Secretion of ADP and ATP is an essential prerequisite for platelet aggregation. Impaired nucleotide secretion can cause aggregation defects and increased bleeding risk. Quantitative determination of platelet nucleotide content and exocytosis is thus of importance for the characterization and diagnosis of bleeding phenotypes. For transgenic animal models with hemostatic defects analysis of potential secretion defects is as well imperative.

METHODS

Supernatants of washed platelets and platelet-rich plasma were analyzed by HPLC for ADP and ATP concentration. Calibration of the HPLC data was accomplished with an internal standard compensating for loss of analyte, detection sensitivity, and interference of the biomatrix.

RESULTS

HPLC analysis of nucleotide secretion was carried out with human and mouse platelets. Detection limits were determined for washed platelet and platelet-rich plasma samples. In the physiological concentration range linearity with respect to the peak area is maintained.

CONCLUSION

The method combines reasonable sensitivity with robustness. The internal standard ensures reliable quantification of nucleotide concentrations even in presence of otherwise interfering substances. The low sample consumption renders possible the application to analysis of small samples like in mouse experiments.

Clinical practice: the bleeding child. Part II: disorders of secondary hemostasis and fibrinolysis

Bleeding complications in children may be caused by disorders of secondary hemostasis or fibrinolysis. Characteristic features in medical history and physical examination, especially of hemophilia, are palpable deep hematomas, bleeding in joints and muscles, and recurrent bleedings. A detailed medical and family history combined with a thorough physical examination is essential to distinguish abnormal from normal bleeding and to decide whether it is necessary to perform diagnostic laboratory evaluation. Initial laboratory tests include prothrombin time and activated partial thromboplastin time. Knowledge of the classical coagulation cascade with its intrinsic, extrinsic, and common pathways, is useful to identify potential defects in the coagulation in order to decide which additional coagulation tests should be performed.